GEOLOGICAL FRAMEWORK OF THE EBRO CONTINENTAL-MARGIN AND SURROUNDING AREAS

The eastern and southeastern margins of Iberia were affected during Neogene time by a rifting tectonic process superimposed on the Alpine structures. The Valencia Trough, situated off the northeastern coast of Iberia, has been defined as a rift system that began its activity in late Oligocene-Early Miocene time. The opening of the Valencia Trough produced a series of tectonic grabens created by fractures which strike parallel to the coastline. As a consequence of the rifting, subsidence occurred and depositional sequences of Miocene age were subsequently deposited over the Triassic and Mesozoic basement. Some of the Mesozoic faults were reactivated and affected the Tertiary deposits. The depositional history was controlled mainly by extensional faulting during the late Paleocene-early Miocene, and by rapid subsidence. During the late Pliocene a second extensional period occurred in the Iberian Chain resulting in the present configuration of the continental margin in the study area. The Pliocene-Quaternary evolution of the margin was largely controlled by fluctuation of the Ebro River sediment supply and sea-level oscillations.